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From build...@apache.org
Subject svn commit: r969694 - in /websites/production/cxf/content: cache/docs.pageCache docs/using-apache-htrace.html
Date Wed, 21 Oct 2015 00:47:27 GMT
Author: buildbot
Date: Wed Oct 21 00:47:27 2015
New Revision: 969694

Log:
Production update by buildbot for cxf

Modified:
    websites/production/cxf/content/cache/docs.pageCache
    websites/production/cxf/content/docs/using-apache-htrace.html

Modified: websites/production/cxf/content/cache/docs.pageCache
==============================================================================
Binary files - no diff available.

Modified: websites/production/cxf/content/docs/using-apache-htrace.html
==============================================================================
--- websites/production/cxf/content/docs/using-apache-htrace.html (original)
+++ websites/production/cxf/content/docs/using-apache-htrace.html Wed Oct 21 00:47:27 2015
@@ -117,11 +117,11 @@ Apache CXF -- Using Apache HTrace
            <!-- Content -->
            <div class="wiki-content">
 <div id="ConfluenceContent"><p><style type="text/css">/*<![CDATA[*/
-div.rbtoc1445384791745 {padding: 0px;}
-div.rbtoc1445384791745 ul {list-style: disc;margin-left: 0px;}
-div.rbtoc1445384791745 li {margin-left: 0px;padding-left: 0px;}
+div.rbtoc1445388408752 {padding: 0px;}
+div.rbtoc1445388408752 ul {list-style: disc;margin-left: 0px;}
+div.rbtoc1445388408752 li {margin-left: 0px;padding-left: 0px;}
 
-/*]]>*/</style></p><div class="toc-macro rbtoc1445384791745">
+/*]]>*/</style></p><div class="toc-macro rbtoc1445388408752">
 <ul class="toc-indentation"><li><a shape="rect" href="#UsingApacheHTrace-Overview">Overview</a></li><li><a
shape="rect" href="#UsingApacheHTrace-DistributedTracinginNutshell">Distributed Tracing
in Nutshell</a></li><li><a shape="rect" href="#UsingApacheHTrace-DistributedTracinginApacheCXF">Distributed
Tracing in Apache CXF</a></li><li><a shape="rect" href="#UsingApacheHTrace-ConfiguringClientconfigure.client">Configuring
Client</a>
 <ul class="toc-indentation"><li><a shape="rect" href="#UsingApacheHTrace-Configuringtracingheadernames">Configuring
tracing header names</a></li></ul>
 </li><li><a shape="rect" href="#UsingApacheHTrace-ConfiguringServerconfigure.server">Configuring
Server</a>
@@ -129,7 +129,7 @@ div.rbtoc1445384791745 li {margin-left:
 </li><li><a shape="rect" href="#UsingApacheHTrace-DistributedTracingInAction:UsageScenarios">Distributed
Tracing In Action: Usage Scenarios</a>
 <ul class="toc-indentation"><li><a shape="rect" href="#UsingApacheHTrace-Example#1:ClientandServerwithdefaultdistributedtracingconfigured">Example
#1: Client and Server with default distributed tracing configured</a></li><li><a
shape="rect" href="#UsingApacheHTrace-Example#2:ClientandServerwithnestedtrace">Example
#2: Client and Server with nested trace</a></li><li><a shape="rect" href="#UsingApacheHTrace-Example#3:ClientandServertracewithtimeline">Example
#3: Client and Server trace with timeline</a></li><li><a shape="rect"
href="#UsingApacheHTrace-Example#4:ClientandServerwithannotatedtrace(key/value)">Example
#4: Client and Server with annotated trace (key/value)</a></li><li><a
shape="rect" href="#UsingApacheHTrace-Example#5:ClientandServerwithparalleltrace(involvingthreadpools)">Example
#5: Client and Server with parallel trace (involving thread pools)</a></li><li><a
shape="rect" href="#UsingApacheHTrace-Example#6:ClientandServerwithasynchronousJAX-RSservice(server-side)">Exampl
 e #6: Client and Server with asynchronous JAX-RS service (server-side)</a></li><li><a
shape="rect" href="#UsingApacheHTrace-Example#7:ClientandServerwithasynchronousinvocation(client-side)">Example
#7: Client and Server with asynchronous invocation (client-side)</a></li></ul>
 </li><li><a shape="rect" href="#UsingApacheHTrace-DistributedTracingandJAX-WSsupport">Distributed
Tracing and JAX-WS support</a></li><li><a shape="rect" href="#UsingApacheHTrace-FutureWork">Future
Work</a></li></ul>
-</div><h1 id="UsingApacheHTrace-Overview">Overview</h1><p><a shape="rect"
class="external-link" href="http://htrace.incubator.apache.org/index.html">Apache HTrace</a>
is a tracing framework intended for use with distributed systems written in java. Since version
<strong>3.1.3</strong>, Apache CXF fully supports integration with <a shape="rect"
class="external-link" href="http://htrace.incubator.apache.org/index.html">Apache HTrace</a>,
both on client side and server side. This section gives a complete overview on how distributed
tracing support is supported in JAX-RS applications built on top of Apache CXF.</p><h1
id="UsingApacheHTrace-DistributedTracinginNutshell">Distributed Tracing in Nutshell</h1><p>Distributed
tracing, first described by Google in <a shape="rect" class="external-link" href="http://research.google.com/pubs/pub36356.html"
rel="nofollow">Dapper, a Large-Scale Distributed Systems Tracing Infrastructure</a>
paper became increasingly important topic these days. With 
 microservices (aka SOA) gaining more and more adoption, the typical applications are built
using dozens or even hundreds of small, distributed pieces. The end-to-end traceability of
the requests (or any kind of work performed on user's behalf) is hard task to accomplish,
particularly taking into account asyncronous or/and concurrent invocations. <a shape="rect"
class="external-link" href="http://htrace.incubator.apache.org/index.html">Apache HTrace</a>
is inspired by <a shape="rect" class="external-link" href="http://research.google.com/pubs/pub36356.html"
rel="nofollow">Dapper, a Large-Scale Distributed Systems Tracing Infrastructure</a>
paper and essentially is a full-fledged distributed tracing framework.</p><p>Distributed
tracing is additional instrumentation layer on top of new or existing applications. In terms
of distributed tracing, <strong>span</strong> represents a basic unit of work.
For example, executing database query is a <strong>span</strong>. <strong>Spans</strong>

 are identified by a unique 64-bit ID for the <strong>span</strong> and another
64-bit ID for the <strong>trace</strong> the span is a <strong>part</strong>
of. <strong>Spans</strong> also have other data, such as <strong>descriptions</strong>,
<strong>timelines</strong>,<strong> key-value annotations</strong>,
the <strong>ID</strong> of the <strong>span</strong> that caused them
(parent), and <strong>process</strong> ID&#8217;s (normally IP address and
process name). Spans are started and stopped, and they keep track of their timing information.
Once <strong>span</strong> is created, it should be stopped at some point in the
future. In turn, <strong>trace</strong> is a set of spans forming a tree-like
structure. For example, if you are running a JAX-RS service, a trace might be formed by a
<strong>PUT</strong> request.</p><p>From implementation prospective,
and in context of Java applications, <strong>spans</strong> are attached to their
threads (in general, thread which created the
  <strong>span</strong> should close it). However it is possible to transfer <strong>spans</strong>
from thread to thread in order to model a complex execution flows. It is also possible to
have many <strong>spans</strong> in the same thread, as long as they are properly
created and closed. In the next sections we are going to see the examples of that.</p><p>Another
two important concepts of in context of distributed tracing are <strong>span receivers</strong>
and <strong>samplers</strong>. Essentially, all spans (including start/stop time,
key/value annotations, timelines, ..) should be persisted (or collected) somewhere. <strong>Span
receiver</strong> is a collector within a process that is the destination of <strong>spans</strong>
when a trace is running (it could be a console, local file, data store, ...). <a shape="rect"
class="external-link" href="http://htrace.incubator.apache.org/index.html">Apache HTrace</a>
provides span receivers for <a shape="rect" class="external-link" h
 ref="http://hbase.apache.org">Apache HBase</a>, <a shape="rect" class="external-link"
href="https://flume.apache.org/">Apache Flume</a> and <a shape="rect" class="external-link"
href="http://zipkin.io/" rel="nofollow">Twitter Zipkin</a>. From other side, <strong>samplers</strong>
allow to control the frequency of the tracing (all the time, never, probability driven, ...).
Using the <strong>sampler</strong> is the way to minimize tracing overhead (or
just amount of traces) by limiting them to particular conditions.</p><h1 id="UsingApacheHTrace-DistributedTracinginApacheCXF">Distributed
Tracing in Apache CXF</h1><p><a shape="rect" href="http://cxf.apache.org/">Apache
CXF</a> is a very popular framework for building services and web APIs. No doubts, it
is going to play even more important role in context of microservices architecture letting
developers to quickly build and deploy individual JAX-RS/JAX-WS services. As it was just mentioned
before, distributed tracing is an essential tec
 hnique to monitor the application as whole, breaking the request to individual service traces
as it goes through and crosses the boundaries of threads, processes and machines.</p><p>The
current integration of distributed tracing in <a shape="rect" href="http://cxf.apache.org/">Apache
CXF</a> supports <a shape="rect" class="external-link" href="http://htrace.incubator.apache.org/index.html">Apache
HTrace</a> only in JAX-RS 2.x applications. From high-level prospective, it consists
of three main parts:</p><ul style="list-style-type: square;"><li><strong>TracerContext</strong>
(injectable through <strong>@Context</strong> annotation)</li><li><strong>HTraceProvider</strong>
(server-side JAX-RS provider) and <strong>HTraceClientProvider</strong> (client-side
JAX-RS provider)</li><li><strong>HTraceFeature</strong> (server-side
<a shape="rect" href="http://cxf.apache.org/">Apache CXF</a> feature to simplify
<a shape="rect" class="external-link" href="http://htrace.incubator.apache.org/inde
 x.html">Apache HTrace</a> configuration and integration)</li></ul><p><a
shape="rect" href="http://cxf.apache.org/">Apache CXF</a> uses HTTP headers to hand
off tracing context from the client to the service and from the service to service. Those
headers are used internally by <strong>HTraceProvider</strong> and <strong>HTraceClientProvider</strong>,
but are configurable. The default header names are declared in the TracerHeaders class:</p><ul
style="list-style-type: square;"><li><strong>X-Span-Id</strong>: contains
a current span ID</li></ul><p>By default, <strong>HTraceProvider</strong>
will try pass the currently active <strong>span</strong> through HTTP headers
on each service invocation. If there is no active span, the new span will be created and passed
through HTTP headers on per-invocation basis. Essentially, just registering the <strong>HTraceProvider</strong>
on the client and <strong>HTraceClientProvider</strong> on the server is enough
to have tracing context to be proper
 ly passed everywhere. The only configuration part which is necessary are <strong>span
receiver(s)</strong> and <strong>sampler</strong>.</p><p>It
is also worth to mention the way <a shape="rect" href="http://cxf.apache.org/">Apache
CXF</a> attaches the description to <strong>spans</strong>. With regards
to the client integration, the description becomes a full URL being invoked prefixed by HTTP
method, for example: <strong>GET </strong><a shape="rect" class="external-link"
href="http://localhost:8282/books" rel="nofollow"><strong>http://localhost:8282</strong>/books</a>.
On the server side integration, the description becomes a relation JAX-RS resource path prefixed
by HTTP method, f.e.: <strong>GET books, POST book/123</strong></p><h1
id="UsingApacheHTrace-ConfiguringClientconfigure.client">Configuring Client <span class="confluence-anchor-link"
id="UsingApacheHTrace-configure.client"></span></h1><p>There are a couple
of way the JAX-RS client could be configured, depending on the c
 lient implementation. <a shape="rect" href="http://cxf.apache.org/">Apache CXF</a>
provides its own <strong>WebClient</strong> which could be configured just like
that (in future versions, there would be a simpler ways to do that using client specific features):</p><div
class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent
pdl">
+</div><h1 id="UsingApacheHTrace-Overview">Overview</h1><p><a shape="rect"
class="external-link" href="http://htrace.incubator.apache.org/index.html">Apache HTrace</a>
is a tracing framework intended for use with distributed systems written in java. Since version
<strong>3.1.3</strong>, Apache CXF fully supports integration with <a shape="rect"
class="external-link" href="http://htrace.incubator.apache.org/index.html">Apache HTrace</a>,
both on client side and server side. This section gives a complete overview on how distributed
tracing support is supported in JAX-RS applications built on top of Apache CXF.</p><h1
id="UsingApacheHTrace-DistributedTracinginNutshell">Distributed Tracing in Nutshell</h1><p>Distributed
tracing, first described by Google in <a shape="rect" class="external-link" href="http://research.google.com/pubs/pub36356.html"
rel="nofollow">Dapper, a Large-Scale Distributed Systems Tracing Infrastructure</a>
paper became increasingly important topic these days. With 
 microservices (aka SOA) gaining more and more adoption, the typical applications are built
using dozens or even hundreds of small, distributed pieces. The end-to-end traceability of
the requests (or any kind of work performed on user's behalf) is hard task to accomplish,
particularly taking into account asyncronous or/and concurrent invocations. <a shape="rect"
class="external-link" href="http://htrace.incubator.apache.org/index.html">Apache HTrace</a>
is inspired by <a shape="rect" class="external-link" href="http://research.google.com/pubs/pub36356.html"
rel="nofollow">Dapper, a Large-Scale Distributed Systems Tracing Infrastructure</a>
paper and essentially is a full-fledged distributed tracing framework.</p><p>Distributed
tracing is additional instrumentation layer on top of new or existing applications. In terms
of distributed tracing, <strong>span</strong> represents a basic unit of work.
For example, executing database query is a <strong>span</strong>. <strong>Spans</strong>

 are identified by a unique 128-bit ID. <strong>Spans</strong> also have other
data, such as <strong>descriptions</strong>, <strong>timelines</strong>,<strong>
key-value annotations</strong>, the <strong>ID</strong> of the <strong>span</strong>
that caused them (parent), and <strong>process/tracer</strong> ID&#8217;s
(normally IP address and process name). Spans are started and stopped, and they keep track
of their timing information. Once <strong>span</strong> is created, it should
be stopped at some point in the future. In turn, <strong>trace</strong> is a set
of spans forming a tree-like structure. For example, if you are running a JAX-RS service,
a trace might be formed by a <strong>PUT</strong> request and downstream work.</p><p>From
implementation prospective, and in context of Java applications, <strong>spans</strong>
are attached to their threads (in general, thread which created the <strong>span</strong>
should close it). However it is possible to transfer <strong>spans</str
 ong> from thread to thread in order to model a complex execution flows. It is also possible
to have many <strong>spans</strong> in the same thread, as long as they are properly
created and closed. In the next sections we are going to see the examples of that.</p><p>Another
two important concepts in context of distributed tracing are <strong>span receivers</strong>
and <strong>samplers</strong>. Essentially, all spans (including start/stop time,
key/value annotations, timelines, ..) should be persisted (or collected) somewhere. <strong>Span
receiver</strong> is a collector within a process that is the destination of <strong>spans</strong>
when a trace is running (it could be a console, local file, data store, ...). <a shape="rect"
class="external-link" href="http://htrace.incubator.apache.org/index.html">Apache HTrace</a>
provides span receivers for <a shape="rect" class="external-link" href="http://hbase.apache.org">Apache
HBase</a>, <a shape="rect" class="external-link" href="https
 ://flume.apache.org/">Apache Flume</a> and <a shape="rect" class="external-link"
href="http://zipkin.io/" rel="nofollow">Twitter Zipkin</a>. From other side, <strong>samplers</strong>
allow to control the frequency of the tracing (all the time, never, probability driven, ...).
Using the <strong>sampler</strong> is the way to minimize tracing overhead (or
just amount of traces) by limiting them to particular conditions.</p><h1 id="UsingApacheHTrace-DistributedTracinginApacheCXF">Distributed
Tracing in Apache CXF</h1><p><a shape="rect" href="http://cxf.apache.org/">Apache
CXF</a> is a very popular framework for building services and web APIs. No doubts, it
is going to play even more important role in context of microservices architecture letting
developers to quickly build and deploy individual JAX-RS/JAX-WS services. As it was just mentioned
before, distributed tracing is an essential technique to monitor the application as whole,
breaking the request to individual service traces as 
 it goes through and crosses the boundaries of threads, processes and machines.</p><p>The
current integration of distributed tracing in <a shape="rect" href="http://cxf.apache.org/">Apache
CXF</a> supports <a shape="rect" class="external-link" href="http://htrace.incubator.apache.org/index.html">Apache
HTrace</a> (<strong>4.x+</strong> release branch) only in JAX-RS 2.x applications.
From high-level prospective, it consists of three main parts:</p><ul style="list-style-type:
square;"><li><strong>TracerContext</strong> (injectable through <strong>@Context</strong>
annotation)</li><li><strong>HTraceProvider</strong> (server-side JAX-RS
provider) and <strong>HTraceClientProvider</strong> (client-side JAX-RS provider)</li><li><strong>HTraceFeature</strong>
(server-side <a shape="rect" href="http://cxf.apache.org/">Apache CXF</a> feature
to simplify <a shape="rect" class="external-link" href="http://htrace.incubator.apache.org/index.html">Apache
HTrace</a> configuration and integration)</
 li></ul><p><a shape="rect" href="http://cxf.apache.org/">Apache CXF</a>
uses HTTP headers to hand off tracing context from the client to the service and from the
service to service. Those headers are used internally by <strong>HTraceProvider</strong>
and <strong>HTraceClientProvider</strong>, but are configurable. The default header
names are declared in the TracerHeaders class:</p><ul style="list-style-type: square;"><li><strong>X-Span-Id</strong>:
contains a current span ID</li></ul><p>By default, <strong>HTraceProvider</strong>
will try to pass the currently active <strong>span</strong> through HTTP headers
on each service invocation. If there is no active spans, the new span will be created and
passed through HTTP headers on per-invocation basis. Essentially, just registering the <strong>HTraceProvider</strong>
on the client and <strong>HTraceClientProvider</strong> on the server is enough
to have tracing context to be properly passed everywhere. The only configuration part whic
 h is necessary are <strong>span receiver(s)</strong> and <strong>sampler</strong>(s).</p><p>It
is also worth to mention the way <a shape="rect" href="http://cxf.apache.org/">Apache
CXF</a> attaches the description to <strong>spans</strong>. With regards
to the client integration, the description becomes a full URL being invoked prefixed by HTTP
method, for example: <strong>GET </strong><a shape="rect" class="external-link"
href="http://localhost:8282/books" rel="nofollow"><strong>http://localhost:8282</strong>/books</a>.
On the server side integration, the description becomes a relation JAX-RS resource path prefixed
by HTTP method, f.e.: <strong>GET books, POST book/123</strong></p><h1
id="UsingApacheHTrace-ConfiguringClientconfigure.client">Configuring Client <span class="confluence-anchor-link"
id="UsingApacheHTrace-configure.client"></span></h1><p>There are a couple
of ways the JAX-RS client could be configured, depending on the client implementation. <a
shape="rect" href="http:/
 /cxf.apache.org/">Apache CXF</a> provides its own <strong>WebClient</strong>
which could be configured just like that (in future versions, there would be a simpler ways
to do that using client specific features):</p><div class="code panel pdl" style="border-width:
1px;"><div class="codeContent panelContent pdl">
 <pre class="brush: java; gutter: false; theme: Default" style="font-size:12px;">final
Map&lt;String, String&gt; properties = new HashMap&lt;String, String&gt;();
 properties.put(Tracer.SPAN_RECEIVER_CLASSES_KEY, ...);
 properties.put(Tracer.SAMPLER_CLASSES_KEY, ...);
@@ -142,7 +142,7 @@ properties.put(Tracer.SAMPLER_CLASSES_KE
  */
         
 final Tracer tracer = new Tracer.Builder()
-    .name("webclient")
+    .name("web-client")
     .conf(HTraceConfiguration.fromMap(properties))
     .build();
                 
@@ -180,7 +180,7 @@ final Response response = client
 <pre class="brush: java; gutter: false; theme: Default" style="font-size:12px;">final
ClientConfiguration config = WebClient.getConfig(client);
 config.getRequestContext().put(TracerHeaders.HEADER_SPAN_ID, "CUSTOM_HEADER_SPAN_ID");
 </pre>
-</div></div><div class="confluence-information-macro confluence-information-macro-warning"><span
class="aui-icon aui-icon-small aui-iconfont-error confluence-information-macro-icon"></span><div
class="confluence-information-macro-body"><p>It is very important to keep client
and server HTTP headers configuration in sync, otherwise the server won't be able to establish
the current tracing context properly.</p></div></div><h1 id="UsingApacheHTrace-ConfiguringServerconfigure.server">Configuring
Server <span class="confluence-anchor-link" id="UsingApacheHTrace-configure.server"></span></h1><p>Server
configuration is a bit simpler than client one thanks to the feature class available,&#160;<strong>HTraceFeature</strong>.
Depending on the way the&#160;<a shape="rect" href="http://cxf.apache.org/">Apache
CXF</a> is used to configure JAX-RS services, it could be part of JAX-RS application
configuration, for example:</p><div class="code panel pdl" style="border-width: 1px;"><div
class="codeCo
 ntent panelContent pdl">
+</div></div><div class="confluence-information-macro confluence-information-macro-warning"><span
class="aui-icon aui-icon-small aui-iconfont-error confluence-information-macro-icon"></span><div
class="confluence-information-macro-body"><p>It is very important to keep client
and server HTTP headers configuration in sync, otherwise the server won't be able to establish
the current tracing context properly.</p></div></div><h1 id="UsingApacheHTrace-ConfiguringServerconfigure.server">Configuring
Server <span class="confluence-anchor-link" id="UsingApacheHTrace-configure.server"></span></h1><p>Server
configuration is a bit simpler than the client one thanks to the feature class available,&#160;<strong>HTraceFeature</strong>.
Depending on the way the&#160;<a shape="rect" href="http://cxf.apache.org/">Apache
CXF</a> is used to configure JAX-RS services, it could be part of JAX-RS application
configuration, for example:</p><div class="code panel pdl" style="border-width: 1px;"><div
class="co
 deContent panelContent pdl">
 <pre class="brush: java; gutter: false; theme: Default" style="font-size:12px;">@ApplicationPath("/")
 public class CatalogApplication extends Application {
     @Override



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